Touch screen device with coating and flexible printed circuit

ABSTRACT

In one embodiment, a touch sensor comprises a beamsplitter operable to reflect a first portion of light incident on the beamsplitter and transmit a second portion of light incident on the beamsplitter, a substrate, and one or more lines of conductive material disposed on the substrate, the lines of conductive material disposed between the first substrate and the beamsplitter.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is continuation of application Ser. No. 16/282,531,filed Feb. 22, 2019, pending, which is a continuation of applicationSer. No. 13/828,021, filed Mar. 14, 2013, now U.S. Pat. No. 10,241,623,each of which is incorporated by reference in its entirety herein.

TECHNICAL FIELD

This disclosure generally relates to touch sensors, and moreparticularly to the reduction of touch sensor pattern visibility usingbeamsplitters.

BACKGROUND

In touch screen configurations with certain touch sensors overlaid on adisplay, such as metal or metal-based touch sensors, the touch sensorsmay reflect light that is incident upon the touch sensors and may causean undesirable view of the display. For instance, the user of a touchscreen device may be able to see the liens of touch sensors overlaid onthe display. This issue is especially prevalent when the display is darkor turned off, or in certain ambient light conditions.

Some current systems may attempt to prevent touch sensor visibilityissues by depositing a dark coating on top of the touch sensors to makethem less reflective. However, this may require additional materialand/or equipment costs. In addition, this process may require carefulcontrol over the coating thickness to avoid losing conductivity, andthus performance, of the sensors. Furthermore, the dark coating maystill be viewable, reducing the overall visual quality of the sensor anddisplay, and certain issues of non-uniformity of the dark coating mayalso produce striping or banding patterns of the touch sensors over thedisplay.

Other current systems for reducing the visibility of touch sensorpatterns may include circular polarizer elements. However, circularpolarizers may largely reduce the amount of light transmitted from theunderlying display, for example by 50% to 60%. In addition, circularpolarizers may only be used in conjunction with non-birefringentsubstrates (e.g., glass, cyclo-olefin polymer (COP), or cyclic olefincopolymers (COC)). Otherwise, they may cause rainbow effects in theimage seen by a user of the device due to birefringence. Furthermore,circular polarizers may be relatively thick, and may be approximately200-300 μm.

Other current systems for reducing the visibility of touch sensorpatterns may include multi-layer stacks of anti-reflection coatings andindex-matched coatings. These multi-layer coatings may be quiteexpensive, however, and may be quite thick.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example touch sensor according to particularembodiments of the present disclosure;

FIGS. 2A-2B illustrate an example touch screen device without abeamsplitter; and

FIGS. 3A-3B illustrate an example touch screen device including abeamsplitter according to particular embodiments of the presentdisclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS

In touch screen configurations with certain touch sensors overlaid on adisplay, such as metal or metal-based touch sensors, the touch sensorsmay reflect light that is incident upon the touch sensors and may causean undesirable view of the display. For instance, the user of a touchscreen device may be able to see the lines of touch sensors overlaid onthe display. This issue is especially prevalent when the display is darkor turned off, or in certain ambient light conditions.

Some current systems may attempt to prevent touch sensor visibilityissues by depositing a dark coating on top of the touch sensors to makethem less reflective. However, this may require additional materialand/or equipment costs. In addition, this process may require carefulcontrol over the coating thickness to avoid losing conductivity, andthus performance, of the sensors. Furthermore, the dark coating maystill be viewable, reducing the overall visual quality of the sensor anddisplay, and certain issues of non-uniformity of the dark coating mayalso produce striping or banding patterns of the touch sensors over thedisplay.

Other current systems for reducing the visibility of touch sensorpatterns may include circular polarizer elements. However, circularpolarizers may largely reduce the amount of light transmitted from theunderlying display, for example by 50% to 60%. In addition, circularpolarizers may only be used in conjunction with non-birefringentsubstrates (e.g., glass, cyclo-olefin polymer (COP), or cyclic olefincopolymers (COC)). Otherwise, they may cause rainbow effects in theimage seen by a user of the device due to birefringence. Furthermore,circular polarizers may be relatively thick, and may be approximately200-300 μm.

Other current systems for reducing the visibility of touch sensorpatterns may include multi-layer stacks of anti-reflection coatings andindex-matched coatings. These multi-layer coatings may be quiteexpensive, however, and may be quite thick.

Accordingly, particular embodiments of the present disclosure may attendto the above problem by placing a beamsplitter or half-mirror coating ontop of lines of touch sensors in order to reduce the display issuescaused by the reflective touch sensor. Typically, touch sensors are mostvisible when a display is relatively dark or is off (e.g., a “black”background). The beamsplitter or half-mirror coating may reduce thevisibility of the touch sensors by reflecting a majority of incidentlight from the beamsplitter and transmitting only a small amount ofincident light through the beamsplitter to the lines of touch sensors,preventing a large amount of light from being reflected by the sensorsand thus preventing a viewer from seeing any reflected touch sensors.For example, in particular embodiments, a beamsplitter coupled to anunderlying display may transmit light from the underlying display whileit is on and maintain a substantially mirrored finish when the displayis off. This effect is based on a differential between the ambient lightand the light coming from the underlying display. If the intensity ofthe light coming from the display is greater than the intensity of thelight shining on the surface (i.e., ambient light), a viewer will beable to see the image behind the beamsplitter. Otherwise, the screenwill take on a shiny, mirrored look to the viewer.

Certain advantages of the present disclosure may include a reduction inthe visibility of the touch sensors overlaying a display withoutcompromising the touch sensor performance or the quality of display.Moreover, by using a beamsplitter according to the present disclosure,there is no further need to apply a dark coating on the touch sensors,which reduces manufacturing time and costs. The present disclosure alsoprevents the need for additional raw materials and/or equipment requiredto coat the touch sensors, and does not require any substantial newmanufacturing investment as it employs a simple step of placing arelatively inexpensive half-mirror coating over the touch sensors.Furthermore, beamsplitters may be manufactured inexpensively on asubstrate with self-adhesive polymer which may prevent fingerprints,dirt, dust, and/or scratches from marking the screen. In addition, thebeamsplitter or coating may be relatively easy to apply or remove andwill not disrupt the touchscreen functions of the device.

A beamsplitter (which may be sometimes known or referred to as ahalf-mirror) may refer to an optical element with a semi-transparentcoating that divides a beam into two or more separate beams. Forexample, a beamsplitter may cause an incident light ray to be dividedinto two rays: one that is reflected by the beamsplitter and one that istransmitted by the beamsplitter. The multiple resulting light rays mayeach comprise a portion of the incident light upon the beamsplitter. Forinstance, in the above example, the reflected ray may comprise 70% ofthe incident ray's power while the transmitted ray may comprise 30% ofthe incident ray's power. Beamsplitter coatings, in some embodiments,may be constructed with dielectric layers on a surface to yield specifictransmission and reflection characteristics. The dielectric nature ofthe coatings may not affect the normal functioning of touch sensor.Reflection proportions for beamsplitters may be in the range from 30% to95%, with the remaining percentage of the light being transmittedthrough the coating without any absorption. In particular embodiments,beamsplitter coatings may be made using dielectric coatings withreflection ranges from 50% to 75% and transmittance ranges from 50% to25%. These ranges of reflection and transmittance may allow forsufficient enough reduction of the visibility of the touch sensor lineswhile also will allowing sufficient contrast ratios for the displayedimages. In certain embodiments, a second surface may then be coated withan anti-reflective coating to reduce “ghost” images.

FIG. 1 illustrates an example touch sensor 110 with an exampletouch-sensor controller 112. Touch sensor 110 and touch-sensorcontroller 112 may detect the presence and location of a touch or theproximity of an object within a touch-sensitive area of touch sensor110. Herein, reference to a touch sensor may encompass both the touchsensor and its touch-sensor controller, where appropriate. Similarly,reference to a touch-sensor controller may encompass both thetouch-sensor controller and its touch sensor, where appropriate. Touchsensor 110 may include one or more touch-sensitive areas, whereappropriate. Touch sensor 110 may include an array of drive and senseelectrodes (or an array of electrodes of a single type) disposed on oneor more substrates, which may be made of a dielectric material. Herein,reference to a touch sensor may encompass both the electrodes of thetouch sensor and the substrate(s) that they are disposed on, whereappropriate. Alternatively, where appropriate, reference to a touchsensor may encompass the electrodes of the touch sensor, but not thesubstrate(s) that they are disposed on.

An electrode (whether a ground electrode, a guard electrode, a driveelectrode, or a sense electrode) may be an area of conductive materialforming a shape, such as for example a disc, square, rectangle, thinline, other suitable shape, or suitable combination of these. One ormore cuts in one or more layers of conductive material may (at least inpart) create the shape of an electrode, and the area of the shape may(at least in part) be bounded by those cuts. In particular embodiments,the conductive material of an electrode may occupy approximately 100% ofthe area of its shape. As an example and not by way of limitation, anelectrode may be made of indium tin oxide (ITO) and the ITO of theelectrode may occupy approximately 100% of the area of its shape(sometimes referred to as 100% fill), where appropriate. In particularembodiments, the conductive material of an electrode may occupysubstantially less than 100% of the area of its shape. As an example andnot by way of limitation, an electrode may be made of fine lines ofmetal or other conductive material (FLM), such as for example copper,silver, or a copper- or silver-based material, and the fine lines ofconductive material may occupy approximately 5% of the area of its shapein a hatched, mesh, or other suitable pattern. Herein, reference to FLMencompasses such material, where appropriate. Although this disclosuredescribes or illustrates particular electrodes made of particularconductive material forming particular shapes with particular fillpercentages having particular patterns, this disclosure contemplates anysuitable electrodes made of any suitable conductive material forming anysuitable shapes with any suitable fill percentages having any suitablepatterns.

Where appropriate, the shapes of the electrodes (or other elements) of atouch sensor may constitute in whole or in part one or moremacro-features of the touch sensor. One or more characteristics of theimplementation of those shapes (such as, for example, the conductivematerials, fills, or patterns within the shapes) may constitute in wholeor in part one or more micro-features of the touch sensor. One or moremacro-features of a touch sensor may determine one or morecharacteristics of its functionality, and one or more micro-features ofthe touch sensor may determine one or more optical features of the touchsensor, such as transmittance, refraction, or reflection.

A mechanical stack may contain the substrate (or multiple substrates)and the conductive material forming the drive or sense electrodes oftouch sensor 110. As an example and not by way of limitation, themechanical stack may include a first layer of optically clear adhesive(OCA) beneath a cover panel. The cover panel may be clear and made of aresilient material suitable for repeated touching, such as for exampleglass, polycarbonate, or poly(methyl methacrylate) (PMMA). Thisdisclosure contemplates any suitable cover panel made of any suitablematerial. The first layer of OCA may be disposed between the cover paneland the substrate with the conductive material forming the drive orsense electrodes. The mechanical stack may also include a second layerof OCA and a dielectric layer (which may be made of PET or anothersuitable material, similar to the substrate with the conductive materialforming the drive or sense electrodes). As an alternative, whereappropriate, a thin coating of a dielectric material may be appliedinstead of the second layer of OCA and the dielectric layer. The secondlayer of OCA may be disposed between the substrate with the conductivematerial making up the drive or sense electrodes and the dielectriclayer, and the dielectric layer may be disposed between the second layerof OCA and an air gap to a display of a device including touch sensor110 and touch-sensor controller 112. As an example only and not by wayof limitation, the cover panel may have a thickness of approximately 1mm; the first layer of OCA may have a thickness of approximately 0.05mm; the substrate with the conductive material forming the drive orsense electrodes may have a thickness of approximately 0.05 mm; thesecond layer of OCA may have a thickness of approximately 0.05 mm; andthe dielectric layer may have a thickness of approximately 0.05 mm.Although this disclosure describes a particular mechanical stack with aparticular number of particular layers made of particular materials andhaving particular thicknesses, this disclosure contemplates any suitablemechanical stack with any suitable number of any suitable layers made ofany suitable materials and having any suitable thicknesses. As anexample and not by way of limitation, in particular embodiments, a layerof adhesive or dielectric may replace the dielectric layer, second layerof OCA, and air gap described above, with there being no air gap to thedisplay.

One or more portions of the substrate of touch sensor 110 may be made ofpolyethylene terephthalate (PET) or another suitable material. Thisdisclosure contemplates any suitable substrate with any suitableportions made of any suitable material. In particular embodiments, thedrive or sense electrodes in touch sensor 110 may be made of ITO inwhole or in part. In particular embodiments, the drive or senseelectrodes in touch sensor 110 may be made of fine lines of metal orother conductive material. As an example and not by way of limitation,one or more portions of the conductive material may be copper orcopper-based and have a thickness of approximately 5 μm or less and awidth of approximately 10 μm or less. As another example, one or moreportions of the conductive material may be silver or silver-based andsimilarly have a thickness of approximately 5 μm or less and a width ofapproximately 10 μm or less. This disclosure contemplates any suitableelectrodes made of any suitable material.

Touch sensor 110 may implement a capacitive form of touch sensing. In amutual-capacitance implementation, touch sensor 110 may include an arrayof drive and sense electrodes forming an array of capacitive nodes. Adrive electrode and a sense electrode may form a capacitive node. Thedrive and sense electrodes forming the capacitive node may come neareach other, but not make electrical contact with each other. Instead,the drive and sense electrodes may be capacitively coupled to each otheracross a space between them. A pulsed or alternating voltage applied tothe drive electrode (by touch-sensor controller 112) may induce a chargeon the sense electrode, and the amount of charge induced may besusceptible to external influence (such as a touch or the proximity ofan object). When an object touches or comes within proximity of thecapacitive node, a change in capacitance may occur at the capacitivenode and touch-sensor controller 112 may measure the change incapacitance. By measuring changes in capacitance throughout the array,touch-sensor controller 112 may determine the position of the touch orproximity within the touch-sensitive area(s) of touch sensor 110.

In a self-capacitance implementation, touch sensor 110 may include anarray of electrodes of a single type that may each form a capacitivenode. When an object touches or comes within proximity of the capacitivenode, a change in self-capacitance may occur at the capacitive node andtouch-sensor controller 112 may measure the change in capacitance, forexample, as a change in the amount of charge needed to raise the voltageat the capacitive node by a pre-determined amount. As with amutual-capacitance implementation, by measuring changes in capacitancethroughout the array, touch-sensor controller 112 may determine theposition of the touch or proximity within the touch-sensitive area(s) oftouch sensor 110. This disclosure contemplates any suitable form ofcapacitive touch sensing, where appropriate.

In particular embodiments, one or more drive electrodes may togetherform a drive line running horizontally or vertically or in any suitableorientation. Similarly, one or more sense electrodes may together form asense line running horizontally or vertically or in any suitableorientation. In particular embodiments, drive lines may runsubstantially perpendicular to sense lines. Herein, reference to a driveline may encompass one or more drive electrodes making up the driveline, and vice versa, where appropriate. Similarly, reference to a senseline may encompass one or more sense electrodes making up the senseline, and vice versa, where appropriate.

Touch sensor 110 may have drive and sense electrodes disposed in apattern on one side of a single substrate. In such a configuration, apair of drive and sense electrodes capacitively coupled to each otheracross a space between them may form a capacitive node. For aself-capacitance implementation, electrodes of only a single type may bedisposed in a pattern on a single substrate. In addition or as analternative to having drive and sense electrodes disposed in a patternon one side of a single substrate, touch sensor 110 may have driveelectrodes disposed in a pattern on one side of a substrate and senseelectrodes disposed in a pattern on another side of the substrate.Moreover, touch sensor 110 may have drive electrodes disposed in apattern on one side of one substrate and sense electrodes disposed in apattern on one side of another substrate. In such configurations, anintersection of a drive electrode and a sense electrode may form acapacitive node. Such an intersection may be a location where the driveelectrode and the sense electrode “cross” or come nearest each other intheir respective planes. The drive and sense electrodes do not makeelectrical contact with each other—instead they are capacitively coupledto each other across a dielectric at the intersection. Although thisdisclosure describes particular configurations of particular electrodesforming particular nodes, this disclosure contemplates any suitableconfiguration of any suitable electrodes forming any suitable nodes.Moreover, this disclosure contemplates any suitable electrodes disposedon any suitable number of any suitable substrates in any suitablepatterns.

As described above, a change in capacitance at a capacitive node oftouch sensor 110 may indicate a touch or proximity input at the positionof the capacitive node. Touch-sensor controller 112 may detect andprocess the change in capacitance to determine the presence and locationof the touch or proximity input. Touch-sensor controller 112 may thencommunicate information about the touch or proximity input to one ormore other components (such one or more central processing units (CPUs))of a device that includes touch sensor 110 and touch-sensor controller112, which may respond to the touch or proximity input by initiating afunction of the device (or an application running on the device).Although this disclosure describes a particular touch-sensor controllerhaving particular functionality with respect to a particular device anda particular touch sensor, this disclosure contemplates any suitabletouch-sensor controller having any suitable functionality with respectto any suitable device and any suitable touch sensor.

Touch-sensor controller 112 may be one or more integrated circuits(ICs), such as for example general-purpose microprocessors,microcontrollers, programmable logic devices or arrays,application-specific ICs (ASICs). In particular embodiments,touch-sensor controller 112 comprises analog circuitry, digital logic,and digital non-volatile memory. In particular embodiments, touch-sensorcontroller 112 is disposed on a flexible printed circuit (FPC) bonded tothe substrate of touch sensor 110, as described below. The FPC may beactive or passive, where appropriate. In particular embodiments,multiple touch-sensor controllers 112 are disposed on the FPC.Touch-sensor controller 112 may include a processor unit, a drive unit,a sense unit, and a storage unit. The drive unit may supply drivesignals to the drive electrodes of touch sensor 110. The sense unit maysense charge at the capacitive nodes of touch sensor 110 and providemeasurement signals to the processor unit representing capacitances atthe capacitive nodes. The processor unit may control the supply of drivesignals to the drive electrodes by the drive unit and processmeasurement signals from the sense unit to detect and process thepresence and location of a touch or proximity input within thetouch-sensitive area(s) of touch sensor 110. The processor unit may alsotrack changes in the position of a touch or proximity input within thetouch-sensitive area(s) of touch sensor 110. The storage unit may storeprogramming for execution by the processor unit, including programmingfor controlling the drive unit to supply drive signals to the driveelectrodes, programming for processing measurement signals from thesense unit, and other suitable programming, where appropriate. Althoughthis disclosure describes a particular touch-sensor controller having aparticular implementation with particular components, this disclosurecontemplates any suitable touch-sensor controller having any suitableimplementation with any suitable components.

Tracks 114 of conductive material disposed on the substrate of touchsensor 110 may couple the drive or sense electrodes of touch sensor 110to connection pads 116, also disposed on the substrate of touch sensor110. As described below, connection pads 116 facilitate coupling oftracks 114 to touch-sensor controller 112. Tracks 114 may extend into oraround (e.g. at the edges of) the touch-sensitive area(s) of touchsensor 110. Particular tracks 114 may provide drive connections forcoupling touch-sensor controller 112 to drive electrodes of touch sensor110, through which the drive unit of touch-sensor controller 112 maysupply drive signals to the drive electrodes. Other tracks 114 mayprovide sense connections for coupling touch-sensor controller 112 tosense electrodes of touch sensor 110, through which the sense unit oftouch-sensor controller 112 may sense charge at the capacitive nodes oftouch sensor 110. Tracks 114 may be made of fine lines of metal or otherconductive material. As an example and not by way of limitation, theconductive material of tracks 114 may be copper or copper-based and havea width of approximately 100 μm or less. As another example, theconductive material of tracks 114 may be silver or silver-based and havea width of approximately 100 μm or less. In particular embodiments,tracks 114 may be made of ITO in whole or in part in addition or as analternative to fine lines of metal or other conductive material.Although this disclosure describes particular tracks made of particularmaterials with particular widths, this disclosure contemplates anysuitable tracks made of any suitable materials with any suitable widths.In addition to tracks 114, touch sensor 110 may include one or moreground lines terminating at a ground connector (which may be aconnection pad 116) at an edge of the substrate of touch sensor 110(similar to tracks 114).

Connection pads 116 may be located along one or more edges of thesubstrate, outside the touch-sensitive area(s) of touch sensor 110. Asdescribed above, touch-sensor controller 112 may be on an FPC.Connection pads 116 may be made of the same material as tracks 114 andmay be bonded to the FPC using an anisotropic conductive film (ACF).Connection 118 may include conductive lines on the FPC couplingtouch-sensor controller 112 to connection pads 116, in turn couplingtouch-sensor controller 112 to tracks 114 and to the drive or senseelectrodes of touch sensor 110. In another embodiment, connection pads116 may be connected to an electro-mechanical connector (such as a zeroinsertion force wire-to-board connector); in this embodiment, connection118 may not need to include an FPC. This disclosure contemplates anysuitable connection 118 between touch-sensor controller 112 and touchsensor 110.

FIGS. 2A-2B illustrate an example touch screen device 200 without abeamsplitter. FIG. 2A illustrates a cross-sectional view of a displaystack 210 that may be used in device 200 illustrated in FIG. 2B. Stack210 comprises a display 201, a substrate 202, a touch sensor mesh 203,and cover 204. Display 201 may be any suitable display for use in atouch screen device such as device 200, and may include a liquid crystaldisplay (LCD). Substrate 202 may be any material suitable for use in atouch screen device such as device 200, and may include a polymermaterial such as polyethylene terephthalate (PET). Sensor mesh 203 mayinclude any suitable mesh of lines of conductive material for sensingtouches on cover 204 by a user of device 200, and may include lines of ametal such as copper or other conductive materials such as ITO, carbonnanotubes, metallic nanowires, nanoribbons, or nanoparticles. Inparticular embodiments, sensor mesh 203 may be coupled to one or moresubstrate materials (not shown), such as polymer materials that includePET. For example, sensor mesh 203 may be coupled to a single side of aPET substrate. As another example, sensor mesh 203 may be disposedbetween two PET substrates. Cover 204 may be any suitable material forcovering and protecting the materials of stack 210, and may includeglass or a polymer material such as PET.

As shown in FIG. 2B, when sensor mesh 203 includes certain touchsensors, such as metal or metal-based touch sensors, the sensors mayreflect light that is incident upon them and may cause an undesirableview of the display. For instance, the user of device 200 may be able tosee the sensor mesh 203 when using device 200. This undesirable effectmay be particularly evident in certain ambient lighting situations, suchas intense ambient light (e.g., using the device outdoors) or when thedisplay is turned off. Accordingly, in particular embodiments, abeamsplitter may be used in the display stack as shown in FIGS. 3A-3Band described further below in order to reduce the visibility of sensormesh 203 when using device 200.

FIGS. 3A-3B illustrate an example touch screen device 300 including abeamsplitter 306 according to embodiments of the present disclosure.FIG. 3A illustrates a cross-sectional view of a display stack 310 thatmay be used in device 300 illustrated in FIG. 3B. Stack 310 comprises adisplay 301, a substrate 302, a touch sensor mesh 303, anti-reflectivecoating 304, cover 305, and beamsplitter 306. Display 201 may be anysuitable display for use in a touch screen device such as device 200,and may include a liquid crystal display (LCD). Substrate 202 may be anymaterial suitable for use in a touch screen device such as device 200,and may include a polymer material such as polyethylene terephthalate(PET). Sensor mesh 203 may include any suitable mesh of lines ofconductive material for sensing touches on cover 204 by a user of device200, and may include lines of a metal such as copper or other conductivematerials such as ITO, carbon nanotubes, metallic nanowires,nanoribbons, or nanoparticles. In particular embodiments, sensor mesh303 may be coupled to one or more substrate materials (not shown), suchas polymer materials that include PET. For example, sensor mesh 303 maybe coupled to a single side of a PET substrate. As another example,sensor mesh 303 may be disposed between two PET substrates. Cover 305may be any suitable material for covering and protecting the materialsof stack 310, and may include glass or a polymer material such as PET.In particular embodiments, cover 305 may act as a substrate forbeamsplitter 306 and/or anti-reflective coating 304.

In certain embodiments, stack 310 may also include an anti-reflectivecoating 304, which may assist in reducing “ghost” images. In someembodiments, anti-reflective coating 304 may be situated above sensormesh 303 but below beamsplitter 306. In the absence of anti-reflectivecoating 304, there may be some reflection from the bottom of cover 305in addition to the light reflected from beamsplitter 306 (i.e., thelight that is not transmitted through beamsplitter 306). This lightreflected from the bottom of cover 305 may cause interference andFresnel loss to the light beam reflected from beamsplitter 306. Thisinterference may cause aberrations in the image seen by a user on thescreen of device 300. Anti-reflective coatings placed on the bottom ofthe cover layer, such as anti-reflective coating 304 shown in FIG. 3A,may prevent such aberrations.

In particular embodiments, the materials in stack 310 may haverefractive indices that are the same or substantially similar to therefractive index of beamsplitter 306. This may help to avoid unwanted orunintended optical phenomena such as reflection or refraction fromoccurring. For instance, in some embodiments, each of substrate 302,anti-reflective coating 304, and cover 305 may have a refractive indexthat is substantially similar to the refractive index of beamsplitter306. As one example, where beamsplitter 306 has a refractive index of1.5, substrate 302 may have a refractive index of 1.57, anti-reflectivecoating 304 may have a refractive index of 1.57, and cover 305 may havea refractive index of 1.52.

Beamsplitter 306 may be any suitable optical element with asemi-transparent coating that divides a beam into two or more separatebeams. In particular embodiments, beamsplitter 306 may cause an incidentlight ray to be divided into two rays: one that is reflected by thebeamsplitter and one that is transmitted by the beamsplitter. In someembodiments, beamsplitter 306 may be constructed using dielectric layerson a surface to yield specific transmission and reflectioncharacteristics. For example, reflection proportions for beamsplitter306 may be in the range from 30% to 95%, with the remaining percentageof the light being transmitted through beamsplitter 306 without anyabsorption. In particular embodiments, beamsplitter 306 may be madeusing dielectric coatings with reflection ranges from 50% to 75% andtransmittance ranges from 50% to 25%. As shown in FIG. 3B, these rangesof reflection and transmittance may allow for sufficient enoughreduction of the visibility of mesh reflection while also will allowingsufficient contrast ratios for the displayed images.

Herein, reference to a non-transitory computer-readable storage mediumor media may include one or more semiconductor-based or other integratedcircuits (ICs) (such, as for example, a field-programmable gate array(FPGA) or an application-specific IC (ASIC)), hard disk drives (HDDs),hybrid hard drives (HHDs), optical discs, optical disc drives (ODDs),magneto-optical discs, magneto-optical drives, floppy diskettes, floppydisk drives (FDDs), magnetic tapes, solid-state drives (SSDs),RAM-drives, SECURE DIGITAL cards, SECURE DIGITAL drives, any othersuitable computer-readable non-transitory storage medium or media, orany suitable combination of two or more of these, where appropriate. Acomputer-readable non-transitory storage medium or media may bevolatile, non-volatile, or a combination of volatile and non-volatile,where appropriate.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,functions, operations, or steps, any of these embodiments may includeany combination or permutation of any of the components, elements,functions, operations, or steps described or illustrated anywhere hereinthat a person having ordinary skill in the art would comprehend.Furthermore, reference in the appended claims to an apparatus or systemor a component of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

1. An apparatus, comprising: a display; a first touch-sensor layercomprising a first plurality of conductive electrodes; a secondtouch-sensor layer comprising a second plurality of conductiveelectrodes; a dielectric coating operable to reflect a first portion oflight incident on the coating and transmit a second portion of lightincident on the coating; wherein the coating is disposed above the firsttouch sensor layer; wherein the coating is on a side of the first touchsensor layer opposite the display; a touch-sensor controller configuredto detect and process the change in capacitance at one or moretouch-sensor nodes to determine the presence and location of atouch-sensor input, and further configured to communicate informationabout the touch-sensor input to one or more components of the apparatus;and a flexible printed circuit electrically connected to thetouch-sensor controller.
 2. The apparatus of claim 1, wherein the firstplurality of conductive electrodes and the second plurality ofconductive electrodes are configured to capacitively couple across thedielectric coating.
 3. The apparatus of claim 1, wherein a layer ofanti-reflective coating is disposed above the first touch-sensor layer.4. The apparatus of claim 3, wherein refractive indices of the coating,the first substrate, and the anti-reflective coating are substantiallysimilar to each other.
 5. The apparatus of claim 1, wherein the secondplurality of conductive electrodes is disposed on a second substrate. 6.The apparatus of claim 1, wherein the second plurality of conductiveelectrodes is disposed on the opposite side of the first substrate. 7.The apparatus of claim 1, wherein the coating is adjacently disposed onthe first touch sensor layer.
 8. The apparatus of claim 1, wherein athird substrate is disposed between the coating and the first touchsensor layer.
 9. The apparatus of claim 1, wherein refractive indices ofthe coating and the first substrate are substantially similar to eachother.
 10. The apparatus of claim 1, wherein the coating comprises ahalf-mirror coating having one or more coating layers disposed above thefirst plurality of conductive electrodes to reduce display issues causedby light reflecting off the first plurality of conductive electrodes.11. A touch sensor device comprising: a coating operable to reflect afirst portion of light incident on the coating and transmit a secondportion of light incident on the coating; a first substrate; and one ormore lines of conductive material disposed on the substrate, the linesof conductive material disposed between the first substrate and thecoating; a touch-sensor controller configured to detect and process thechange in capacitance at one or more touch-sensor nodes in response to atouch-sensor input, and further configured to output information aboutthe touch-sensor input; and a flexible printed circuit electricallyconnected to the touch-sensor controller.
 12. The touch sensor device ofclaim 11, wherein the conductive material is selected from the groupconsisting of: metal, indium tin oxide, or carbon nanotubes.
 13. Thetouch sensor device of claim 11, wherein the first portion of light isin the range of 50% to 75%, and the second portion of light is in therange of 25% to 50%.
 14. The touch sensor device of claim 11, whereinthe one or more lines of conductive material comprises a first set oflines of conductive material and a second set of lines of conductivematerial, the first set of lines disposed above the substrate, thesecond set of lines disposed below the substrate.
 15. The touch sensordevice of claim 11, further comprising an anti-reflective coatingdisposed between the coating and the one or more lines.
 16. The touchsensor device of claim 15, further comprising a substrate disposedbetween the coating and the anti-reflective coating.
 17. The touchsensor device of claim 16, wherein refractive indices of the coating,the substrate, and the anti-reflective coating are substantially similarto each other.
 18. A touch screen device comprising: a coating operableto reflect a first portion of incident light and transmit a secondportion of incident light incident; a touch sensor comprising one ormore lines of conductive material disposed between the display and thecoating; a touch-sensor controller operable to apply a voltage to atleast a portion of the conductive material; and a flexible printedcircuit electrically connected to the touch-sensor controller.
 19. Thedevice of claim 18, further comprising: an anti-reflective coatingdisposed between the coating and the one or more lines.
 20. The deviceof claim 19, further comprising: a substrate disposed between thecoating and the anti-reflective coating; wherein refractive indices ofthe coating, the substrate, and the anti-reflective coating aresubstantially similar to each other.